Field of the Invention
The invention relates to a device forming a clamping pad, of the type comprising a first face to be secured by suction to a worktable and a second face to be secured by suction to a workpiece.
Description of the Related Art
Documents EP 1 342 533 A1 and WO 2007/028 886 A1 describe automatic machines for working materials in sheet or plate form, in which the materials to be worked are positioned and held by double-sided clamping pads. Double-sided clamping pads comprise a top suction cup and a bottom suction cup. The top and bottom suction cups are connected to air and vacuum pipes. The suction that makes it possible to fasten the clamping pad to the worktable and the workpiece to be fastened to the clamping pad is obtained by pumping through side suction pipes, and the presence of those pipes on the worktable leads to a risk of a suction pipe catching the machining tool and may lead to a risk of accident for the operator of the machine-tool. Attempts are made to avoid those risks by pressing the suction pipes onto the machining surface by parts or wedges pressing thereon. However, the pipes pressed on the machining surface retain dust, sludge, and swarf, entrained by the machining lubrification fluid, and that harms the quality of work.
Finally, it has been envisaged to arrange a plurality of orifices opening out into the worktable and to use the orifices in register with the suction cups to convey the suction through said orifices. Although that arrangement gives satisfaction, it does not make it possible to place the positioning pads in any desired position. In addition, the orifices used are liable to become soiled and thus to impede correct operation of the positioning pad.